Mechanisms of visual transduction will be investigated at a number of levels. Photochemistry of the chromophore associated with visual pigments will be studied through photochemical and photophysical studies of polyenes which serve as models for the chromophore. Visual pigments themselves will also be studied primarily through the use of nanosecond laser photolysis techniques. Various photolysis intermediates will be investigated from early intermediates which last for nanoseconds, to later intermediates which are found on the microsecond and millisecond time scales. These intermediates will be characterized in the hope of learning how light results in changing visual pigments to their activated forms. The interactions of these activated visual pigments with other proteins present in visual cells as well as interactons between these other proteins will also be investigated with the use of light scattering techniques combined with microscopy studies. It is hoped that these studies as a whole will provide valuable information on how visual transduction works.